Sou konsepsyon an ak aplikasyon nan sistèm mezi tèrmokouplaj Capteur mezi

Kòm yon eleman tipik mezire tanperati, Capteur a thermocouple te lajman itilize .
Sa ki anba la a se yon sistèm mezi tipik tanperati ki kontwole pa yon mikro sèl chip, ki gen ladann twa pati: (1) mezi anplifikatè sikwi; (2) A/D sikwi konvèsyon; (3) Display Awondisman . Li se lajman ki itilize nan mezi tanperati ak sistèm kontwòl tanperati nan plant pouvwa ak plant chimik .
1. konsepsyon pyès ki nan konpitè
(1) Capteur tanperati thermocouple
This system uses nickel-chromium-nickel-silicon thermocouples. The measured temperature range is 0-655℃. The cold end compensation adopts the compensation bridge method. The potential generated by the unbalanced bridge is used to compensate for the change in thermoelectric potential caused by the change in the cold end temperature of Thermocouple a . pon an dezekilib konsiste de kat pon bra nan rezistans R1, R2, R3 (Manganèz kwiv fil ± 0 degre, ak r 1= r 2= R 3=1 ω {{16} Thermocouples . pon an anjeneral balanse nan 20 degre . Nan moman sa a, kat rezistans pon pon an nan pon an se r 1= r 2= R 3= RCU, epi pa gen okenn pwodiksyon nan fen ak Bomè, lè yo te soti nan fen a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè sa a, lè yo te soti nan fen a, lè yo te soti nan fen a, epi yo te gen yon sèl. Rises, RCU ogmante, pandan y ap potansyèl la thermoelectric nan tèrmokouple a diminye kòm tanperati a fen frèt ogmante . UAB ki egal a diminye nan potansyèl la tèrmo, ak potansyèl la pwodiksyon rete chanje apre yo finn supèrpoze sou ou a pou ou pa gen okenn.
(2) mezi anplifikatè sikwi
Nan sikui aktyèl, pwodiksyon siyal la soti nan tèrmokaple a se pa plis pase yon dè dizèn kèk nan millivolts (<30mV), and contains common-mode interference such as power frequency, static electricity and magnetic coupling. To amplify this kind of circuit, the amplifier circuit needs to have a high common-mode rejection ratio, high gain, low noise and high input impedance. Therefore, a measurement amplifier circuit is suitable. The measurement amplifier is also called a data amplifier, instrument amplifier and bridge amplifier. It has a high input impedance and is easy to match with various signal sources. Its input offset voltage, input offset current and input bias current are small, and the temperature drift is small. Due to the small time temperature drift, the measurement amplifier has good stability. The measurement amplifier is composed of three op amps, and the differential input terminals R1 and R2 are connected to the in-phase terminals of A1 and A2 respectively. The input impedance is very high, a symmetrical circuit structure is used, and the measured signal is directly added to the input terminal, thereby ensuring a strong ability to suppress common-mode signals. A3 is actually a differential follower, and its gain is approximately 1. The gain of the measuring amplifier is: AV=V0/(V2-V1), AV=Rf/R(1+(Rf1+Rf2)/RW). In this circuit, as long as the performance of op amps A1 and A2 is symmetrical (mainly referring to input impedance and voltage gain), their drift will be greatly reduced. They have high input impedance and common mode rejection ratio, are very sensitive to tiny differential mode voltage, and are suitable for measuring signals transmitted over long distances. Therefore, they are very easy to use with sensors with tiny outputs. RW is an external resistor used to adjust the gain, and a multi-turn potentiometer is used here.
Nan kous aktyèl la, A1 ak A2 itilize ba-flote, segondè-presizyon op amp op {{4} se lajman ki itilize nan entegrasyon ki estab, adisyon presizyon, deteksyon konparezon ak anplifikasyon presizyon nan siyal fèb . op -07 mande pou ekipman pou pouvwa doub, ak seri a tanperati opere se 0-70 degre . Ajisteman . A3 itilize 741 chip, ki mande pou ekipman pou pouvwa doub, ak ranje a ekipman pou pouvwa a se ± (3-18) v . ekipman pou pouvwa tipik la se ± 15v, ki ta dwe jeneralman pi plis pase oswa egal a ± 5v {{}} {
(3) A/D (Analog-a-dijital) Konvèsyon Awondisman
Siyal la vòltaj anplifye pa anplifikatè a mezi gen yon seri vòltaj nan 0-5 V . siyal sa a se yon siyal analòg epi yo pa ka aksepte pa òdinatè a, se konsa A/D konvèsyon yo dwe fè . nan Awondisman aktyèl la, ICL7109 chip, {{{ Low-Drift, pri ki ba-double-integral 12- ti jan A/D konvètisè . Depi aktyèl la 12- ti kras apwoksimasyon siksesif A/D konvètisè se relativman chè, bon mache a Doub-integral 12- ti jan A/D. Sistèm mezi pou divès siyal Capteur tankou peze, mezire presyon, ak mezire tanperati .
Atravè analiz ki pi wo a nan sistèm nan mezi tanperati Capteur thermocouple, mwen espere ke li pral itil nan travay tout moun ak etid .